The proposed research project will identify outer membrane proteins of Haemophilus influenzae Type b (Hib) which have potential for 3se as vaccinogens to protect against systemic Hib disease. Outer membranes of this organism will be purified by isopycnic sedimentation in sucrose density gradients, and the protein content of these outer membranes will be analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The outer membrane proteins which are exposed on the surface of the intact Hib cell will be identified by extrinsic radiolabelling techniques. Those cell surface-exposed Hib outer membrane proteins which are immunogenic in infant rats will be identified by the use of a radioimmunoprecipitation technique used in conjunction with SDS-PAGE. Those cell surface-exposed Hib outer membrane proteins which are shown to be immunogenic will be purified for use as experimental vaccinogens in animal protection tests. These proteins will be purified by an immunoaffinity technique employing monoclonal antibodies produced by lymphocyte hybridomas. Lymphocyte hybridomas secreting monoclonal antibodies directed against the desired Hib outer membrane proteins will be constructed by fusing mouse myeloma cells to spleen cells from Hib-immunized mice.